I set my bass strap so when I am standing the bass is in the same position as it is if I am sitting and resting it on my lap. Too low is basically a recipe for sloppiness or bending your wrist in a position that might end up causing trouble for you down the road. Suer it "looks cool" but is really not when you consider all the negatives. Too high makes you look like a jazz weenie
I don't recall where I saw the recommendation for the way I wear my bass but it was from a well known bass player. Try it and I think most players would agree it is a very comfortable postion. It also gives you the benefit of always having the bass in the same position whether you are sitting down at practice or on stage for a gig.